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Original question:

AWR1642BOOST: Configuration file used to do Range Bias and Rx Channel Gain/Offset Measurement and Compensation

CCS/AWR1642BOOST: Do not understand the code of MmwDemo_rxChanPhaseBiasCompensation and some angle algorithm principle

user5916025
Prodigy 230 points
Part Number: AWR1642BOOST

Tool/software: Code Composer Studio

Hi

For the function MmwDemo_rxChanPhaseBiasCompensation, I don't understand the theory of this role.

In addition, I would like to ask you where to search for "Rx channel gain/phase offset compensation".

There is another question that makes me very confused.

When we use FFT to calculate the angle and velocity of an object, we use the phase effect caused by the tiny distance, where the velocity is the distance that the object moves in a short time, and the angle is a small

distance between the antennas.

From this we can see that the subtle influence is very important for us to calculate the angle and speed, so we will use Doppler compensation in the process of calculating the angle, because if we do not do this compensation, the angle we calculate will also be affected.

The following is my question.

When we are doing angle estimation, our basic assumption is that because the distance is far enough, the return wave is parallel for each antenna.

Through this parallel estimation, we get the difference of the object travel between different antennas is "the distance of the antenna * sin (the angle of the object)", and use FFT to calculate the phase difference affected by this short distance, and then calculate the angle.

In fact, the return waves cannot be parallel, and such a situation will certainly affect the larger than the distance of the antenna *sin (the angle of the object). How can we ensure that the angle we calculate is correct?

Regards

Paul

  • 0
    TI__Guru 69990 points
    Hi,
    Please provide us some time to revert to you on this question.

    Thanks for your patience.

    Regards,
    Jitendra
  • 0
    TI__Expert 4720 points

    Hi Paul,

    MmwDemo_rxChanPhaseBiasCompensation - is a simple way to externally calibrate the sensor. Every receiver in the sensor may experience a slightly different delay (due to board/antenna imperfections). These errors manifest in the 2D-FFT output as a difference in phase/amplitude of the sample corresponding to a target across different receivers.

    In order to correct these errors, we put a target (a corner reflector) in a known location (directly opposite the radar). In such a case the phase of all samples corresponding to the target should be the same, their amplitudes should also be the same. If they aren't equal, we can then compute the correction factor for phase error. This is done using the CLI- APIs  compRangeBiasAndRxChanPhase and measureRangeBiasAndRxChanPhase (check the mmwaveSDK user-guide for more information). 

    Regarding your second question, please read up on the nearFieldCfg CLI-API (again from the mmwaveSDK user-guide).

    Regards

    Anil